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X-rays, body scans and radiation

Ionising radiation is a type of radiation called ‘high energy’. The high energy that ionising radiation has means it can affect our cells, including mutating DNA which can lead to cancer.

There are different types of ionising radiation, including gamma rays and x-rays. These types of ionising radiation can cause cancer.

It’s important to remember that we are exposed to radiation from natural sources every day. Radon gas from the earth’s crust contributes the largest amount of natural radiation to most people living in the UK. Cosmic rays from the sun, stars and outer space, natural radiation from the food we eat, the water we drink and the ground we walk on, also contribute to our natural exposure every day.

To help avoid the potential health effects of ionising radiation, any man-made exposures are tightly regulated.

Can X-rays and medical imaging increase the risk of cancer?

Medical x-rays and other types of imaging are very important to help diagnose different illnesses, including cancer. Some types of imaging, including X-rays and CT scans (Computed Tomography) use ionising radiation. The health risks from the radiation the imaging equipment uses are generally very low, and usually outweighed by the benefits of getting the right diagnosis and appropriate treatment.

The dose received from medical imaging is usually less than what we'd be exposed to naturally over a few days or years (depending on the type). Although medical x-rays add some extra radiation on top of this, they also bring great benefits to patients. But even so, unnecessary x-rays should be avoided.

Common types of medical x-rays

There are different types of medical imaging tests using x-rays that you may come across:

Radiography to look at broken bones or your teeth and chest.

Mammography to screen for breast cancers.

Computed tomography (CT) to detect different diseases, including some cancers

Fluoroscopy, such as a barium x-rays to look at your digestive system

How much radiation does an x-ray give out?

These tests all involve different amounts of radiation. The level of risk from the radiation you receive will also depend on:

The area of the body - for example x-rays of the chest pose a lower risk than x-rays of the pelvis
Age - young patients are at more risk. Unborn babies are also at higher risk so you should tell your doctor if you are pregnant
Gender - women have a slightly higher lifetime risk of developing radiation-induced cancers than men

In the UK, the Health Protection Agency monitors the amount of radiation we receive from x-rays and makes sure they are as safe as possible. The average radiation dose now is half the level it was in the 1980s. You can find out more about radiation from medical x-rays on the Health Protection Agency website.

Are there ways to limit radiation if I need an x-ray?

When possible, your doctors will recommend other types of imaging that don’t use radiation, for example using ultrasound or magnetic resonance imaging (MRI scan). But in some cases an x-ray is the best way to do the job.

If you are concerned about having a large number of x-rays, you should talk to your doctor about it. You should also tell your doctor of previous x-rays you may have had. They may be useful for diagnosing, managing or treating your current condition. And they may mean that you do not need to have more x-ray tests.

What are the risks of commercially available body scans?

Some commercial companies offer ‘full body’ CT scans to the public. These are available to people even if they are not recommended by their doctor, and they are not medically necessary. CT scans have risks, and when they are not needed or done on people with no medical symptoms, they are likely to do more harm than good.

A ‘full body’ CT scan uses 500 times the amount of radiation of a single chest x-ray. This may be necessary for people with a genuine medical need. But for healthy individuals without medical symptoms, the risks generally outweigh the benefits. And while scans are helpful for finding out what is causing a symptom, if people have no symptoms to investigate they can flag up harmless abnormalities, or conditions which would never have caused you any problems. So they may lead to unnecessary tests and treatment.

Do airport body scanners use radiation?

Body scanners are at use in many airports across the UK and abroad. There are two types of scanner in use in the UK. One type uses millimetre radio waves that can “see” through clothing. The other type uses a very low dose of ionising radiation. Neither type has been shown to pose a risk to people’s health.

The first type of scanner uses radio waves, which are a form of non-ionising radiation that does not cause health effects at the low doses given off by airport scanners. Read more about non-ionising radiation, such as that used in mobile phones, wifi and power lines.

The second type uses ionising radiation, which in high doses can be harmful. But the levels used in airport scanners are about 100,000 times lower than what an average UK person would be exposed to each year. This dose is so low that it makes no noticeable difference to a person’s risk of cancer.

Does air travel expose people to radiation?

Flying on a commercial airline is a safe way to travel and is unlikely to affect your risk of cancer.

The Earth receives a lot of ‘cosmic radiation’ from space but our atmosphere shields us from most of this. The atmosphere thins the higher you get, so someone flying in a plane would receive more cosmic radiation than someone on the ground.

A passenger would still get a very small amount of radiation, but the low level of radiation that they would experience is very unlikely to seriously affect their cancer risk, even if they were a frequent flyer.

Do pilots and air cabin crew have higher cancer risks?

Pilots and air cabin crew spend much more time in the air and are exposed to much more radiation than passengers are. But even airline pilots are exposed to radiation levels well within safe limits.

However, some studies have suggested that pilots and air cabin crew may have a higher risk of skin cancer than other people. Female air cabin staff may also have a slightly higher risk of breast cancer.

It is unlikely that these risks are due to radiation. The types of cancer that air crew may be at higher risk of are different to the types of cancer linked to radiation.

Sun exposure is the main cause of skin cancers and cabin crew may spend more time in sunnier climates than other people.

Working in air crews may disrupt body clocks and alter hormone levels, which could explain the possible increased breast cancer risks in stewardesses.

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